WASHINGTON, U.S. - Commenting on the federal probe into Russia’s role in the 2016 U.S. Presidential election, Donald Trump has said that he believes investigators will find nothing at the end of it.

He, yet again, denied charges of collusion and said there was no collusion between his campaign and Russia.

Trump even denied ever asking FBI Director James B. Comey to back off on his agency’s investigation into former national security adviser Michael Flynn.

Trump’s comments came immediately after Deputy Attorney General Rod J. Rosenstein announced his decision to appoint a special counsel to investigate the case.

Addressing a joint news conference with President Juan Manuel Santos of Colombia, Trump said, “I respect the move, but the entire thing has been a witch hunt, and there is no collusion between — certainly myself and my campaign, but I can only speak for myself and the Russians. Zero. Believe me, there’s no collusion.”

After being confirmed by an overwhelming vote of 94 to 6 - Justice Department’s second-highest-ranking official, Rosenstein came under harsh criticism for doing the White House’s bidding after he drafted a memo criticizing Comey’s handling of the Hillary Clinton email probe last year.

Rosenstein’s memo was used as a justification for the FBI chief’s dismissal by the White House, before Trump sabotaged the White House press operation that was trying to defend him, taking matters into his own hand and even blindsiding his own vice president with his shifting reasoning.

Rosenstein’s move to appoint former FBI boss Robert Mueller as special counsel to oversee the Russia inquiry is being seen as an attempt by him to salvage his bruised reputation.

Following his decision, Rosenstein, who held an unusual 90-minute closed briefing with most of the 100 senators, told the full Senate that the White House’s initial account of Comey’s firing was not accurate because he said he knew that Comey would be fired before he wrote a controversial memo that the White House used as its justification for the dismissal.

Rosenstein told the senators that Trump had decided to fire Comey the day before he wrote his memo.

He emphasised the independent authority that the new special counsel — former FBI director and federal prosecutor Robert S. Mueller III — has in the Russian investigation while addressing senators in a secure room in the Capitol Visitors Center.

Senate Minority Leader Charles E. Schumer (D-N.Y.) said, “If one thing is clear from the meeting we just had, it is that Mr. Mueller has broad and wide-ranging authority to follow the facts wherever they go. That gives me confidence and should give the American people some confidence.”

Further, Sen. Claire McCaskill (D-Mo.) said Rosenstein “was very careful about not going into any details surrounding the removal because he wants to give Robert Mueller the opportunity to make an independent decision” about how to proceed.

The appointment of a special counsel distances the probe from Attorney General Jeff Sessions, who earlier this year, recused himself from any role in the inquiry after reports stated that, much like Flynn, Sessions too had failed to disclose conversations with Russia’s ambassador to the U.S.

The deputy attorney general is also said to have notified the White House of Mueller’s appointment only after he signed the order designating him as special counsel.

Releasing the order to the media, Rosenstein said in a statement, “What I have determined is that based upon the unique circumstances, the public interest requires me to place this investigation under the authority of a person who exercises a degree of independence from the normal chain of command.”

In his role as the special counsel in the probe, Mueller has been given broad powers to issue subpoenas, present evidence to a grand jury, call witnesses and bring charges - all the powers of a federal prosecutor.

His authority extends broadly to include “any links and/or coordination between the Russian government and individuals associated with the campaign of President Donald Trump.”

In the news conference meanwhile, Trump said, “Director Comey was very unpopular with most people. I also got a very, very strong recommendation, as you know, from the deputy attorney general, Rod J. Rosenstein.”

He expressed surprise that he had not received bipartisan support for his decision to fire Comey and called the suggestion he had done anything potentially worthy of criminal charges “totally ridiculous.”

Earlier the same day, Trump took to Twitter to comment on the news of the special prosecutor, calling the move a politically motivated “witch hunt” by his Democratic rivals.